Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.

Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.

Automotive Calculators

Turbo Horsepower Calculator

2026-09-27 6 min

Boosted horsepower from NA baseline, boost and intercooler effectiveness — predict the gain before buying.

Boosted Power: 466 hp
Power Gain: 166 hp; Added by boost

Calculator

NA Power(hp)

Boost(psi)

psi

Intercooler Eff.(%)

Results update live as you type

Live statistics

Boosted Power

466 hp

Power Gain

166 hp

Added by boost

Results

Optimal

Boosted Power

466hp

Power Gain

166hp

Added by boost

Planning estimate from standard automotive formulas. Validate with dyno, timeslip or datalog data when precision matters.

Visualizations

Results overview

466.3Boosted Power

166.3Power Gain

Boosted Power vs. NA Power

Boosted Power

466.3hp

01,200

Formula

Power scales with charge density: pressure ratio discounted by unrecovered compressor heat.

HP_boosted = HP_NA × PR × [1 − (1 − eff) × 0.25]

Variables

Symbol	Name	Unit	Description
HP_NA	Baseline	hp	Naturally aspirated power
PR	Pressure ratio	:1	From boost
eff	IC effectiveness	%	Heat removed

Explanation

No intercooler (eff 0) forfeits ~25% of boost’s promise to heat; a great IC recovers nearly all of it.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Record the inputs.

NA Power:300 hp

Boost:10 psi

Intercooler Eff.:70 %

Result: 3 inputs ready

Step 2

Apply the formula.

HP_boosted = HP_NA × PR × [1 − (1 − eff) × 0.25]

Result: Primary result = 466 hp

Step 3

Read every derived output.

Boosted Power:466 hp

Power Gain:166 hp

Result: Boosted Power = 466 hp

Final Answer

466

Worked Examples

See how the calculator works with different scenarios.

Scenario

300 NA, 10 psi, 70% IC.

Inputs

NA:300 hp

Boost:10 psi

IC:70%

Calculation

PR = 1.68; density = 1.68 × 0.925 = 1.554; HP = 466

Result

466 hp (+166).

Interpretation

The classic 50%-plus street-turbo gain.

Understanding Your Result

Your Result: Boosted Power: 466 hp

What This Means

Expected flywheel power under boost.

Why It Matters

Validates turbo, fuel and build budgets against the goal before spending.

Professional Interpretation

Treat the primary result as a planning estimate, then validate on a dyno, at the track, or with logged sensor data. If measured numbers disagree by more than ~10%, re-check inputs (units are the usual culprit) before changing parts.

Recommendations

•Double-check units on every input before trusting the result
•Compare against the worked example below to sanity-check magnitude
•Validate with measured data (dyno, timeslip, datalog) when it matters

Learn — fuel economy, deeply

Boosted power is density arithmetic: more oxygen per revolution, minus the heat tax.

1 · Where the gallon goes (energy path)

Engine heat

60–70% lost

Coolant + exhaust carry most energy away. Hybrids recover some via Atkinson cycle + regen.

Driveline

5–15% lost

Transmission, differential, accessories. CVTs and 8–10 speed autos lose less.

Aero drag

∝ v²

Doubles from 55→78 mph. Roof boxes hurt more than trunks.

Rolling + brakes

10–20%

Tires, weight, stops. Regen braking (hybrid/EV) reclaims city braking energy.

4 · Measure like a pro (the 3-tank protocol)

Fill to first click at the same pump, record the odometer (Tank 0).
Drive normally for 2–3 tanks; always refill to first click at the same pump.
MPG = total miles ÷ total gallons across all tanks — averaging kills pump-click noise.
Cross-check with the trip computer; a persistent >10% gap means the computer needs calibration — or the car needs service.
Log with an OBD-II dongle for per-trip MPG if you want to isolate commute vs. highway behavior.

Practical Tips

•Start from the default values — they describe a typical combination
•Use the sensitivity chart to see which input moves the result most
•Keep units consistent (all inches or all mm, never mixed)

Common Mistakes

Mixing units (inches with mm, psi with kPa)

Convert every input to the unit shown on its field before calculating.

Trusting a single output blindly

Cross-check with the worked example and, when it matters, a dyno or datalog.

Assumptions

This calculator makes the following assumptions to provide estimates:

Steady-state model: Formulas assume stabilized conditions; transients, heat soak and traction limits are excluded.

Standard factors: Empirical constants (BSFC, VE, drivetrain loss) use typical values — your combination may differ.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: Predictions carry real-world scatter of roughly ±5–15% depending on the model.

No transient effects: Shift time, wheelspin, spool lag and heat soak are not modeled here.

Frequently Asked Questions

Answers to common questions about this calculator.

Double the air = double power?

Nearly, minus heat, backpressure and friction — typically 85–95% of ideal.

Octane limit?

Pump gas caps effective compression — check Boost-to-Compression and Knock Margin pages.

Related Calculators

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Related Guides

Deepen your understanding with these educational resources.

Automotive Guides

Build planning, measurement protocol and validation how-tos

Glossary

Technical terms used in mortgage calculations explained in plain language.

MPG: Miles per gallon. Distance travelled per gallon of fuel; higher is better. US gallon = 3.785 L.
L/100 km: Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.
MPGe: Miles per gallon-equivalent. EV metric: miles travelled on 33.7 kWh (energy of 1 gal of gasoline).
CAFE: Corporate Average Fuel Economy — US fleet-average efficiency standard enforced by NHTSA.
Rolling resistance: Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.
Aerodynamic drag: Air resistance growing with the square of speed — why highway MPG falls fast above 60 mph.
Hypermiling: Driving techniques (coasting, steady speed, anticipation) that maximise real-world MPG.
OBD-II: On-board diagnostics port. Scanners and dongles read live MPG, fuel trim and fault codes.

Authoritative References

Trusted sources and standards referenced by this calculator.

EPA — FuelEconomy.gov DOE — Fuel-Efficient Driving Tips NHTSA — Driving Safety & Efficiency SAE International — Fuel Economy Standards Consumer Reports — MPG Truth IRS — Standard Mileage Rates

Applicable Standards

EPA Fuel Economy Testing (40 CFR Part 600)CAFE — Corporate Average Fuel Economy Standards (NHTSA)WLTP — Worldwide Harmonised Light Vehicle Test ProcedureSAE J1321 / J1711 — Fuel consumption test proceduresISO 2575 — Road vehicles symbols & efficiency markings

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Page Information

Last Updated:

2026-09-27

Version:

2.0.0

References:

License:

Free to use for educational and professional purposes.